Hello,
I take look on the bq24193's datasheet and I think it is almost perfect IC for intended application. STC3115 seems to by quite cheap but not the best solution.
We currently have quite outdated, but still better battery gas gauging design based on BQ34Z100.
Documentation is here http://www.mlab.cz/Modules/PowerSupply/LION1CELL01A/DOC/LION1CELL01A.pdf
I think the main work should be the redesign of our LION1CELL01A module with bq24193 charger integrated in it. We should do it in KiCAD probably in form of new MLAB module (for testing). The exact PCB for Libre laptop should be derived from it then.
Is current blocks/circuit schematic of Libre laptop somewhere? I do not understand how the higher voltages (+5V) or +12 (for LCD) are efficiently generated from battery? Has this design higher efficiency than two balanced cells connected in series?
2016-02-28 23:54 GMT+01:00 Luke Kenneth Casson Leighton lkcl@lkcl.net:
ok, well actually there is a sub-task that i could do with your help on: i need a 15 watt *single-cell* battery charger / monitor board which is compliant with the USB-OTG Power specification up to 3A @ 5.0V and can be controlled via I2C as to which direction the power goes... *and* can take DC input at the same time. i've found the bq24193, it's the best i could yet find that will do the job. the only thing is, its I2C interface is hard-wired to 1.8v and i need 3.0 to 3.3v, so there will be some level-shifting needed there. it also will need a battery monitor (coulomb counter) - the STC3115 QFN is what i had in mind, but if you have something better please do say so.
PCB size needs to be no bigger than 32 x 85mm, 1.5mm thickness, 2 layer *ONLY*, components *ONLY* on one side, no through-hole components or connectors are allowed, and there is a severe [hard] height limit of 5.5mm so the only DC connector i could find which can handle 5A and is within that limit is the PJ-018H-SMT from CUI Inc.
also, i really loved the solar panel idea and it turns out that the PJ-018H-SMT has a 3-pin arrangement, so in theory a diode and a solar panel in series between pins 2 and 3 would provide solar power when the DC-jack is disconnected. pin 3 (to which the solar panel would be wired) would be disconnected when the DC jack is in. pin 2 is GND.
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On Wed, Mar 2, 2016 at 12:15 PM, Jakub Kákona kaklik@mlab.cz wrote:
Hello,
I take look on the bq24193's datasheet and I think it is almost perfect IC for intended application.
good to hear. there are some variants btw - bq24192, 24191, 24196 - it would be good if you could double-check which one is best. the USB-OTG functionality @ 3A is *critical* because EOMA68's 5V power rail is *REVERSIBLE*. basically you can either *PROVIDE* 5V power or the CPU cards can be *PROVIDED WITH* power.
so i am using the USB-OTG rail of the bq2419x series to provide up to 15W of power to the *entire* laptop.
STC3115 seems to by quite cheap but not the best solution.
We currently have quite outdated, but still better battery gas gauging design based on BQ34Z100.
if you've got something better, _great_.
Documentation is here http://www.mlab.cz/Modules/PowerSupply/LION1CELL01A/DOC/LION1CELL01A.pdf
looks great. it's almost the right size as well.
I think the main work should be the redesign of our LION1CELL01A module with bq24193 charger integrated in it. We should do it in KiCAD probably in form of new MLAB module (for testing). The exact PCB for Libre laptop should be derived from it then.
.... it's almost perfect as-is. if you can keep the bits which should not go into the laptop on a snap-off area along the bottom of the PCB then it's pretty much done already.
Is current blocks/circuit schematic of Libre laptop somewhere?
honestly... you're the first person ever to ask. i'll generate some schematic PDFs and point you at them shortly. i will also document the pinouts of the various connectors, as that will be part of the specification for the Power PCB.
I do not understand how the higher voltages (+5V) or +12 (for LCD) are efficiently generated from battery?
the LCD is only 4 watts (despite being 15.6in), backlight is around 3W, and when run at only 30hz the LCD uses under 1W. a single simple step-up converter to around 17-20v @ 150mA constant current is therefore perfectly ok, from a 5V supply.
this is *not* a monstrous "let's burn the user's eyes out with a 20W backlight and dazzle them with 5W worth of 3480x2000 pixels @120fps needing 5GHZ worth of bandwidth".
so i've used a Silergy SY7201 (or equivalent), it's a SOT23-6, it's got a power dissipation rating of 0.4W - it does the job.
+5V comes from the USB-OTG function of the bq24193. that can provide up to 3A, which is perfect, and is exactly what's needed. so there is no need for a 5V regulator.
the "normal" power output is battery-level (4.2v) and does *not* need to be stepped up. it goes straight (solely and exclusively) to PCB2 - the "Embedded Controller" board. this is actually a 3.3v part, so there is a 3.3v regulator.
basically the EC board - which manages power, keyboard, touchscreen, and provides RTC functionality etc - is the *only* thing which needs continuous power, so that's run off of the bq24193's "main output".
the EC board is where the I2C interface goes [NOT to the EOMA68 CPU Card!]. so it is the EC's job to perform "on / off" function. the *EC* controls the CPU Card's power state. the *EC* tells the bq24193 to switch the USB-OTG power to 5V @ 3A. the *EC* listens to the battery status (from the bq34z100).
basically, this is *not* a "standard laptop", it's an "embedded" design. so there is no 5V rail, and there is no 12V rail: embedded power ICs for single-cell applications can therefore be considered.
Has this design higher efficiency than two balanced cells connected in series?
given that the maximum power required is only 15W, which is within the budget of the bq2419x series, i am more concerned about simplicity of design (and completing this product) than i am about running efficiency. a 2-cell design is far more complex to design - apart from anything, 2 cells would need to be sourced of exactly the right size, and it took me months to find even the current battery.
later however, once this first laptop is out the door, i will begin a 2nd design which will need something like a 30 to 35 watt budget (more USB ports, built-in SSD, etc.) and at that point a 2-cell or 3-cell design is going to be needed. however, the implications for that design decision are MASSIVE. the casework - which has already taken well over a year to complete - would need a total overhaul.
l.
argh - the bq2419x series only provides up to 1.5A @ 5V in USB-OTG mode, not 3A. which rules it out. it's otherwise perfect, damnit. i'll have another search - bq2416x series isn't good enough as it only does 2.5A.
i'm currently updating http://rhombus-tech.net/community_ideas/laptop_15in/ to add connector specifications. PDF schematics and layout image links: http://hands.com/~lkcl/eoma/laptop_15in/laptop_15in_PCB3_rev2_1.pdf http://hands.com/~lkcl/eoma/laptop_15in/pcb3_layout.png http://hands.com/~lkcl/eoma/laptop_15in/laptop_15in_PCB2_2.pdf
l.
En 2 de marzo de 2016 en 14:44:13, Luke Kenneth Casson Leighton (lkcl@lkcl.net) escrito:
argh - the bq2419x series only provides up to 1.5A @ 5V in USB-OTG mode, not 3A. which rules it out. it's otherwise perfect, damnit. i'll have another search - bq2416x series isn't good enough as it only does 2.5A.
i'm currently updating http://rhombus-tech.net/community_ideas/laptop_15in/ to add connector specifications. PDF schematics and layout image links: http://hands.com/~lkcl/eoma/laptop_15in/laptop_15in_PCB3_rev2_1.pdf
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http://hands.com/~lkcl/eoma/laptop_15in/pcb3_layout.png http://hands.com/~lkcl/eoma/laptop_15in/laptop_15in_PCB2_2.pdf
l.
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On Wed, Mar 2, 2016 at 3:52 PM, GaCuest gacuest@gmail.com wrote:
En 2 de marzo de 2016 en 14:44:13, Luke Kenneth Casson Leighton (lkcl@lkcl.net) escrito:
argh - the bq2419x series only provides up to 1.5A @ 5V in USB-OTG mode, not 3A. which rules it out. it's otherwise perfect, damnit. i'll have another search - bq2416x series isn't good enough as it only does 2.5A.
i'm currently updating http://rhombus-tech.net/community_ideas/laptop_15in/ to add connector specifications. PDF schematics and layout image links: http://hands.com/~lkcl/eoma/laptop_15in/laptop_15in_PCB3_rev2_1.pdf
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sorted, thx.
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On Wed, Mar 2, 2016 at 1:43 PM, Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:
argh - the bq2419x series only provides up to 1.5A @ 5V in USB-OTG mode, not 3A. which rules it out. it's otherwise perfect, damnit.
ok, i thought about this, and i reckon that it'd be ok to do this:
* use the USB-OTG "boost mode" to provide USB-OTG power to the EOMA68 CPU Card [only] * put the SYS-V output through to the main PCB1, where it will do boost conversion to 5.0V for USB ICs. SYS-V output could go directly into the step-up converter for the LCD backlight, and also directly into the 3.3v regulator.
so... the spec doesn't change, just the implementation of PCB1.
l.
Hi, It looks like power schema I expect that is already been done. But a current design is still not fully clear to me. I will probably print the schematics PDFs on large A3 sheets tomorrow and try to find out how the Libre internals are interconnected currently..
Thanks
2016-03-02 16:59 GMT+01:00 Luke Kenneth Casson Leighton lkcl@lkcl.net:
crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
On Wed, Mar 2, 2016 at 1:43 PM, Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:
argh - the bq2419x series only provides up to 1.5A @ 5V in USB-OTG mode, not 3A. which rules it out. it's otherwise perfect, damnit.
ok, i thought about this, and i reckon that it'd be ok to do this:
- use the USB-OTG "boost mode" to provide USB-OTG power to the EOMA68
CPU Card [only]
- put the SYS-V output through to the main PCB1, where it will do
boost conversion to 5.0V for USB ICs. SYS-V output could go directly into the step-up converter for the LCD backlight, and also directly into the 3.3v regulator.
so... the spec doesn't change, just the implementation of PCB1.
l.
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On Wed, Mar 2, 2016 at 4:25 PM, Jakub Kákona kaklik@mlab.cz wrote:
Hi, It looks like power schema I expect that is already been done.
it hasn't. you're missing some history (dating back several months). the LTC4155 was chosen because the datasheet *CLAIMED* that it was compliant with USB-OTG power provision. however, what they neglected to state was that USB-OTG power is *DISABLED* when a 5V DC input is plugged in.
basically, replace LTC4155 with bq24193, and STC3115 with BQ34Z100.
the only complication is that there will need to be a bi-directional Open Drain level shifter to convert the GPIOs for the bq24193. e.g. a TXS0104E.
why is a level shifter needed? because the bq24193 operates its GPIO at 1.8V, and the STM32F072 operates its GPIO at 3.3v. so the I2C and GPIO signals from the bq24193 need to go through a level-shifter. it needs to be bi-directional because SDA (I2C data) is bi-directional.
for the BQ34Z100, apparently it can take REGIN as a reference voltage. so, for this, the Reference Voltage from the EC board (VREF_3V3) should be hooked directly to this pin. that takes care of the GPIO voltage levels for the BQ34Z100.
But a current design is still not fully clear to me.
as this is a complex inter-dependent 4-PCB design with 18 months of design work in 3 of the PCBs and 4 years design work in the EOMA68 standard, that is not surprising.
however, fortunately, the only part that you need to be absolutely clear on is the Power PCB.
if you'd like me to fully explain the full design i'm happy to do so.... just bear in mind that it may take some time.
I will probably print the schematics PDFs on large A3 sheets tomorrow and try to find out how the Libre internals are interconnected currently..
by then phil should have had a chance to update the wiki and bring it out of broken-ness. in the meantime i'm attaching the pcbs.mdwn page which contains the specifications of the connectors. you only need to be concerned about PCB2-to-PCB3 and PCB1-to-PCB3. PCB1-to-PCB2 is for how the EOMA68 CPU Card and the Embedded Controller talk to each other.
l.
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On Wed, Mar 2, 2016 at 4:48 PM, Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:
On Wed, Mar 2, 2016 at 4:25 PM, Jakub Kákona kaklik@mlab.cz wrote:
But a current design is still not fully clear to me.
ok i've created a diagram, it's basically identical to the current PCB3 schematic, except LTC4155 is replaced by a combination of bq24193 plus txs0104 plus 1.8v regulator, and STC3115 is replace by BQ34Z100.
http://hands.com/~lkcl/eoma/laptop_15in/pcb3_diagram.png
key differences from what you *might* be expecting this Charger PCB to have:
1) there is NO 5V rail. 2) there is NO 12V rail 3 ) there is NO 3.3v rail 4) the (appx) 4.2V "SYS" voltage from the Charger IC goes straight out *as-is* 5) Digital GPIO requires a REF voltage to be safe and meaningful. this *has* to be EXTERNALLY SUPPLIED. 6) many devices are now USB-OTG compliant (2-way power), so that is a power output (***AND POWER INPUT***)
from what you wrote, you *may* have considered that something like this would be useful:
1) 5V DC output 2) 12V DC output 3) 3.3v output 4) DC charging input
such a board is not useful for this project, because such a design is for a standard laptop. this isn't a standard laptop, it's a USB-OTG-powered "embedded" device.
l.
Thanks for the diagram! But I have one more question. Is it really necessarily to operate bq24193's I²C bus at 1.8V? According to datasheet http://www.ti.com/lit/ds/symlink/bq24193.pdf The 1.8V was used only as example of operating voltage.. The Absolute Maximum Ratings for all SDA, SCL and INT pins is 7V and both are "i2c standard open collectors" and could be pulled-up to any rail within the operating voltage range.. Therefore I think the Voltage translator is not necessary...
Kaklik
2016-03-02 19:20 GMT+01:00 Luke Kenneth Casson Leighton lkcl@lkcl.net:
crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
On Wed, Mar 2, 2016 at 4:48 PM, Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:
On Wed, Mar 2, 2016 at 4:25 PM, Jakub Kákona kaklik@mlab.cz wrote:
But a current design is still not fully clear to me.
ok i've created a diagram, it's basically identical to the current PCB3 schematic, except LTC4155 is replaced by a combination of bq24193 plus txs0104 plus 1.8v regulator, and STC3115 is replace by BQ34Z100.
http://hands.com/~lkcl/eoma/laptop_15in/pcb3_diagram.png
key differences from what you *might* be expecting this Charger PCB to have:
- there is NO 5V rail.
- there is NO 12V rail
3 ) there is NO 3.3v rail 4) the (appx) 4.2V "SYS" voltage from the Charger IC goes straight out *as-is* 5) Digital GPIO requires a REF voltage to be safe and meaningful. this *has* to be EXTERNALLY SUPPLIED. 6) many devices are now USB-OTG compliant (2-way power), so that is a power output (***AND POWER INPUT***)
from what you wrote, you *may* have considered that something like this would be useful:
- 5V DC output
- 12V DC output
- 3.3v output
- DC charging input
such a board is not useful for this project, because such a design is for a standard laptop. this isn't a standard laptop, it's a USB-OTG-powered "embedded" device.
l.
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On Wed, Mar 2, 2016 at 10:49 PM, Jakub Kákona kaklik@mlab.cz wrote:
Thanks for the diagram!
no problem.
But I have one more question. Is it really necessarily to operate bq24193's I²C bus at 1.8V?
i don't know! :)
According to datasheet http://www.ti.com/lit/ds/symlink/bq24193.pdf The 1.8V was used only as example of operating voltage.. The Absolute Maximum Ratings for all SDA, SCL and INT pins is 7V and both are "i2c standard open collectors" and could be pulled-up to any rail within the operating voltage range.. Therefore I think the Voltage translator is not necessary...
if you reckon an STM32F072 could handle it, then fine. that saves at least 2 ICs, which is great. if you'd like to actually test it, STM32F072-NUCLEO boards are only $EUR 10 from rs-online, mouser, arrow and digikey.
ok, so key question: what sort of timescale do you think you'd be able to do this in? reason i ask is, i need to work out the timeline.
practical matters: i used eurocircuits to get the PCBs done, they were about 7-10 days (unless you pay extra), and around $EUR 70 for QTY2. i have some components (connectors, switches, capacitors) i can send you.
more practical matters: from mid-april i'm going to be moving to a new country *every month* until the end of the year, to track getting this into a first production run.
l.
What is primary function of STM32F072 MCU? Is in necessary for LCD configuration? Is it STM32F072's firmware already written? I am pretty sure in fact - I²C should be operated on only one voltage level ~3V3. But I do not know how the data from battery management I²C bus goes to the EOMA68 card.
What EDA software are you using? The circuit sheets has very unusual graphic style. It would be good if we work in common design tool.
Timescale: I expect two iteration in PCB design. One of local PCB manufacturers offer prototyping service as 36 EUR per 1dm² of two sided PCB. http://www.pragoboard.cz/en/pool_servis Two pcs of planned PCBs probably fits well in to this area. Standard manufacturing time is 7 days. Therefore for purpose of time planning I expect the fully functional PCB design at the end of March or on first week in April.
Shipping: I do not know the price of shipping costs to you. But I have address in Prague (Czech Republic) ZIP code: 18100
I expect the price of shipping will be equivalent to value of connectors or other passive components, therefore sending it separately won't have much sense.
2016-03-03 0:10 GMT+01:00 Luke Kenneth Casson Leighton lkcl@lkcl.net:
On Wed, Mar 2, 2016 at 10:49 PM, Jakub Kákona kaklik@mlab.cz wrote:
Thanks for the diagram!
no problem.
But I have one more question. Is it really necessarily to operate
bq24193's
I²C bus at 1.8V?
i don't know! :)
According to datasheet http://www.ti.com/lit/ds/symlink/bq24193.pdf The 1.8V was used only as example of operating voltage.. The Absolute Maximum Ratings for all SDA, SCL and INT pins is 7V and both are "i2c standard open collectors" and could be pulled-up to any rail
within
the operating voltage range.. Therefore I think the Voltage translator is not necessary...
if you reckon an STM32F072 could handle it, then fine. that saves at least 2 ICs, which is great. if you'd like to actually test it, STM32F072-NUCLEO boards are only $EUR 10 from rs-online, mouser, arrow and digikey.
ok, so key question: what sort of timescale do you think you'd be able to do this in? reason i ask is, i need to work out the timeline.
practical matters: i used eurocircuits to get the PCBs done, they were about 7-10 days (unless you pay extra), and around $EUR 70 for QTY2. i have some components (connectors, switches, capacitors) i can send you.
more practical matters: from mid-april i'm going to be moving to a new country *every month* until the end of the year, to track getting this into a first production run.
l.
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On Thu, Mar 3, 2016 at 10:06 AM, Jakub Kákona kaklik@mlab.cz wrote:
What is primary function of STM32F072 MCU?
functions PLURAL.
* real-time clock * power manager (on/off, emergency reset) * battery manager * keyboard * trackpad and mouse buttons (all handled by a 3.5in LCD with a built-in CTP)
Is in necessary for LCD configuration?
the mouse trackpad is not a trackpad, it is a 480x272 3.5in LCD with a Capacative Touchpanel. this LCD must be configured and programmed to display buttons and scrollbars.
you may be confusing this EC-controlled 3.5in 480x272 LCD with the main laptop's 15.6in 1366x768 LCD. the one that's controlled by the EC is the touchpanel one (mouse trackpad). the one that's controlled by the main PCB is the main laptop LCD.
the two are **NOT** linked in any way, shape or form.
Is it STM32F072's firmware already written?
partially. it's available as GPLv3+ source code.
I am pretty sure in fact - I²C should be operated on only one voltage level ~3V3.
it's not - the voltage level is chosen by the IC designer, or... well, look at the datasheet of the variable-voltage I2C EEPROM ICs for an example. they run anywhere between 1.2 and 5.0v and the I2C high / low levels are usually 0.7x and 0.3x the VREF voltage.
But I do not know how the data from battery management I²C bus goes to the EOMA68 card.
via the USB interface of the STM32F072. the STM32F072 can emulate up to 7 different end-points, so currently i have:
* USB CDCACM - this comes up as /dev/ttyUSB0 on GNU/Linux and connecting to it you can read status info.... such as battery data * USB HID Keyboard - the keyboard
i still have to do the mouse end-point.
What EDA software are you using? The circuit sheets has very unusual graphic style. It would be good if we work in common design tool.
if you use KiCAD i will reluctantly install it. KiCAD is "simple" enough to do this job. the developers have chosen a path that will keep it from ever being used for any kind of professional-grade product development.
Timescale: I expect two iteration in PCB design. One of local PCB manufacturers offer prototyping service as 36 EUR per 1dm² of two sided PCB. http://www.pragoboard.cz/en/pool_servis
cool. local is great.
Two pcs of planned PCBs probably fits well in to this area. Standard manufacturing time is 7 days. Therefore for purpose of time planning I expect the fully functional PCB design at the end of March or on first week in April.
fantastic
Shipping: I do not know the price of shipping costs to you. But I have address in Prague (Czech Republic) ZIP code: 18100
I expect the price of shipping will be equivalent to value of connectors or other passive components, therefore sending it separately won't have much sense.
ok.... the only thing is, one of the switches (a right-angle tactile switch) is hard to get hold of in Europe. remember that this is targetted at mass-volume, *not* at the "let's sell 1,000 and be happy... therefore we'll get everything on digikey @ a 2 to 10x markup and be happy" market, so some of the parts i've chosen have to be chosen because they're available in huge volumes in china.
if however you can find a right-angle tactile switch that's available world-wide... great. if not, i'll give you the P/N of the one i found.
l.
hi jakub,
http://rhombus-tech.net/community_ideas/laptop_15in/pcbs/
here's pictures of the current layout, you can see i made a couple of mistakes - most glaringly-obvious one is the battery connector had to go over some components, second is that i have the power-output connector to PCB1 in the wrong place.
i've added some notes for you at the above page, ok?
l.
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On Wed, Mar 2, 2016 at 1:43 PM, Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:
i'm currently updating http://rhombus-tech.net/community_ideas/laptop_15in/ to add connector specifications.
... which i've moved to http://rhombus-tech.net/community_ideas/laptop_15in/pcbs/
but there is currently a synchronisation error in ikiwiki, please do NOT edit the wiki for the moment.
PDF schematics and layout image links: http://hands.com/~lkcl/eoma/laptop_15in/laptop_15in_PCB3_rev2_1.pdf http://hands.com/~lkcl/eoma/laptop_15in/pcb3_layout.png http://hands.com/~lkcl/eoma/laptop_15in/laptop_15in_PCB2_2.pdf
l.
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